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Exposure to Silica Dust Among Construction Workers

In the detailed study published in the Annals of Work Exposures and Health (2023), researchers Emily J. Cothern, William J. Brazile, and Daniel A. Autenrieth investigate the effectiveness of mandated control methods for managing silica dust exposure among construction workers. This exploration, titled “The Evaluation of Worker Exposure to Airborne Silica Dust During Five OSHA Table I Construction Tasks,” not only evaluates adherence to OSHA’s standards but also seeks to understand how background silica affects overall exposure levels.

Study Context and Methodology

Silica dust, a potent hazard in the construction industry, can lead to severe respiratory diseases such as silicosis, lung cancer, and chronic obstructive pulmonary disease. To mitigate these risks, the Occupational Safety and Health Administration (OSHA) set forth a respirable crystalline silica standard for construction that includes permissible exposure limits (PEL) and action levels (AL). OSHA’s Table 1 prescribes specific engineering controls and work practices to reduce silica exposure, ideally eliminating the need for extensive exposure monitoring.

The study involved 19 construction workers at a northern Colorado site, where 51 personal air samples were collected while workers performed five different tasks specified under OSHA’s Table 1. These tasks included core drilling, cutting with a walk-behind saw, dowel drilling, grinding, and jackhammering. Each task was assessed for adherence to prescribed control methods, and air samples were analyzed to determine silica exposure levels.

Key Findings

Despite adherence to OSHA’s specified controls, the study revealed concerning results:

• Approximately 47.1% of workers were exposed to silica above OSHA’s action level, and 29.4% were above the permissible exposure limit when exposures were extrapolated to an eight-hour shift.
• Even with OSHA-specified engineering controls in place, tasks such as grinding showed significantly high silica exposure levels, with average concentrations reaching 172 μg/m³, far exceeding the PEL of 50 μg/m³.
• Background silica concentrations at construction sites also significantly contributed to overexposures, challenging the efficacy of current control measures.

Implications for Construction Safety

These findings underscore a critical gap in the effectiveness of current silica exposure controls under real-world conditions. While OSHA’s Table 1 controls are based on an assumption of efficacy, actual exposures often exceed safe limits, suggesting that these controls may not be sufficient to protect workers from the health risks associated with silica dust.

Recommendations for Improved Safety Practices

The study’s insights lead to several recommendations for enhancing worker safety:

• Enhanced Monitoring: Despite the guidelines, the study highlights the need for regular exposure monitoring to ensure that controls are effective and worker health is not compromised.
• Reevaluation of Control Measures: There is a need for ongoing assessment and improvement of prescribed control measures, especially for high-risk tasks such as grinding.
• Background Silica Management: The influence of background silica suggests that worksite-wide controls, beyond individual task-level measures, are necessary to comprehensively reduce exposure.

Concluding Thoughts

The research conducted by Cothern, Brazile, and Autenrieth provides vital data that challenges the assumption that compliance with OSHA’s Table 1 controls is sufficient to protect workers from silica exposure. It calls for a broader and more dynamic approach to managing silica risks in the construction industry, emphasizing that protective measures must evolve in response to empirical evidence of their effectiveness. This study is a call to action for policymakers, industry leaders, and safety professionals to reexamine and enhance the standards and practices intended to safeguard construction workers from one of the most pervasive health hazards in their field.